Swimming fin



Jan. 10, 1956 Filed Feb. 25, 1953 W. SCHMITZ SWIMMING FIN 2 Sheets-Sheet l INVENTOR.

Jan. 10, 1956 w. SCHMITZ 2,729,832

SWIMMING FIN Filed Feb. 25. 1955 2 Sheets-Sheet 2 INVFNTOR. Walter ficfzmz'tz,

ATTYS.

United States. Patent Office 2,729,832 Patented Jjan. 1 5,6

SWIMMING. FIN

Walter Schmitz, Rheydt (Rheinland), Germany Application February 25,1953, Serial No. 338,824

Claims priority, application Germany February 28,1952

7- Claims. ((19-21) The invention relates to a swinnning fin as a driving means for swimming objects, preferably for attachment to the feet of swimmers or the like.

There are known swimming fins whose, fin blade 60.1. tinues' in the direction of the foot after attachment to the same, that means extends. substantially parallel to and, in the plane of the sole of the foot. Consequently, in the. normal attitude of the foot the fin blade is directed more or less transverse to the path of swimming. To be, able to swin correctly with the known fin, it is neces-. sary to keep the feet stretched in they elongation of the leg when crawling to avoid the braking efiect of the: fin blade which otherwise is directed transverse to the path of travel. But it is not possible even for the most experienced swimmer to keep the feet stretched backwards longer than during a short time, On account of tiring the foot soon returns into the normal position. Thereby are produced eddies of water during the, process of swimming. The known fin constitutes more or less a diving fin for short use.

The invention has for its object a swimming and propulsive fin as a driving means which considerably facilitates the process of swimming. The essential feature of the invention consists therein that the fin blade is angularly arranged towards the front part and dowm. wards. The angular arrangement may preferably be provided under an angle ofabout 25-50 with the plane of the sole of the foot. it has been seen that considerably better results may be obtained in swimming with the aid of the fin according to the invention than with the usual fins. The fin according to the invention does not form as until now an elongation of the plane of the sole of the foot, but forms in swimming an elongation of the leg and with that of the whole body. Merely the short piece of the foot in its normal position does not conform to the direction of movement. But this fact does not reduce the swimming performance as on the one hand the foot slopes in the direction of swimming and on the other hand the normal position of the foot imparts a much greater movablenes's, because the foot in its normal position is much less strained in actuating the fin than the foot which is forcibly kept in a stretched position. While the usual fins raise the water behind the foot, there occurs much less raising of water when using the fin according to the invention. This fin visibly works more in the direction of movement and enables unobtrusive gliding. The fin may be easily handled and assures a complete drive.

Taking into consideration that the fin besides giving the fin blade an appropriate position in the water in the longitudinal axis of the body, shall also enable the bearer of the same to walk or stand, it appears to be suitable to provide the angularly arranged fin blade in a middle position on the foot so that the protruding toes do not hinder too much the stream of water. The axis of the fin blade advantageously lies within the range between the ball and the middle of the foot. Between the foot support or shoe-like member of the fin and the n blade is p e b y ar a ge tow rds, the. rom a. s re p r v block p nv whi h may r s he. toes... A. sw mming fin including flje toes may be manufactured as a, l s r bber hoe wh ch may nc ose, h l of. he. from. part of the foot when standing on tiptoe. It may alsobe chosen an open structure leaving free the toes. but the front part of the foot shall essentially assist the, effect of the fins and for this reason the angular arrange,- ment of the fin blade beneath the ball. of the foot is the best.

The fin blade, may extend symmetrically. to. the foot. But it is also possible that the tin blade extends un; ym c lly to e ng udina a o he. t ot, hat means extends towards one side. This oblique posi; tion of the fin blade is. advantageous in so far as in crawling the feet may be held closely tOgQther Without the fin blades disturbing one another.

The fin according to the invention is preferably made from rubber and may or may not, be provided with a stiflFener. The fin blade is suitably provided with a plurality of longitudinal ribs converging towards the free; end of the fin. The ribs may be arranged on. one, side or on both sides of the fin blade. Further the ribs may have diminishing strength and height towards the mid; dle, line of the fin blade to increase the elasticity of the fin simultaneously with the corresponding effect of the. ribs.

By providing the fin blade with ribs, gradually cont. verging towards the free end, it is obtained that in actuating the fin the stream of water striking against the. fin blade is divided into bands and that these bands are pressed together. Thereby the fin blade PIQdlJQQS. SO- called solid Water bands and presses them during the snake-like up and down movement so, that strong re; actionary effects result. The shoe-like member of the fin receiving the front part of the foot is preferably pro.-. vided witha broad elastic. ban which surrounds the, tendon of Achilles above the heel. Further the, shoe-.. like member of the fin may be divided on the instep a d tied. up. y means of strin s or the. like.

Fig; l is a side el'evational view of the swimming fin with the shoe-like portion thereof mounted on the foot of a user, the normal position of the fin being substantially parallel with the longitudinal axis of the leg as shown in full lines, with movements shown by dotted lines,

Fig. 2 is a top plan view showing ribs extending lengthwise of the fin blade and converging toward the free end thereof, with the fin blade symmetrical to the shoe-like portion,

Fig. 3 is a cross-sectional view taken on line 33 of Fig. 2, showing the longitudinally extending ribs prog'ecting from opposite sides of the fin blade,

Figs. 3a and 312 show the fin blade flexible in opposite directions,

Fig. 4 is a top plan view of a modified construction, showing the fin-like blade projecting forwardly and laterally of the shoe-like portion and with a lacing closure for the shoe-like portion,

Fig. 5 is a cross-sectional view taken on line 5-5 of Fig. 4, showing the longitudinal ribs at the side marginal edges of the fin-like blade being of increased height with the ribs decreasing in height toward the longitudinal axis of the fin like blade, and

Fig. 6 is a top plan view of another form of the finlike blade similar to Fig. 2 with parallel oblique cross ribs between the longitudinally extending ribs.

The fin according to the invention essentially consists of a shoe-like member 1 receiving the foot 2 and of a fin blade 3. According to the invention the fin blade extends in the elongation of the leg if the foot is only somewhat stretched, that is if the foot is stretched in a comfortable manner. The angle included with the sole surface of the foot may amount to about 25-50.

The fin blade 3 which essentially may be formed like a paddle is provided with longitudinal ribs 4 on opposite faces converging towards the free end of the fin blade. In this manner the stream of water passing along the fin blade is seized and guided between two ribs at a time. The constant reduction of the space between the ribs results in pressing together the stream of water. By moving the fin forwards and backwards, thereby can be produced so-called solid water bands aiding the prepulsive effort. Between the fiin blade and the front part of the shoe-like member 1 is suitably arranged a more or less plastic block 5 from rubber or the like to provide a positive support for the foot in the whole range from the ball down to the toes. If the outer ribs 4 are made very thick or. higher as shown in Fig. 5 and the inner ribs are formed somewhat shorter, a fin blade is obtained which may be given a hollow shape dependent on the movement of the blade, whereby an increase of the solid water bands may be obtained. The elastic yielding of the centre of the paddle results in a curved pressure acting upon the encountered water. Between the ribs 4 may be provided further angular ribs 8 extending like fish-bones towards the centre as shown in Fig. 6.

Fig. 4 shows a swimming fin with a fin blade 6 which extends unsymmetrically, or towards one side with respect to the longitudinal axis of the foot and has the angular arrangement of ribs according to Fig. 1. The axis of the fin blade 6 may be arranged under different angles with respect to the longitudinal axis of the foot or of the shoe-like member 1 of the fin respectively. Also, the shoe-like member 1 as shown in Fig. 4, may be split at the top with the sections secured together by a lacing 7.

I claim:

1. A swimming fin comprising a shoe-like member having an open toe portion adapted to be attached to a foot of the user, a flexible fin blade extending outwardly from the bottom of the shoe-like member in proximity to the open toe portion and lying wholly within the forward half portion of the shoe-like member, the angularity of the fin blade relative to the plane of the bottom of the shoe-like member being in the range of 25 to 50 with the point of intersection of the planes of the fin blade and bottom of the shoe-like member lying above the bottom of the shoe-like member and said fin blade normally occupying a position in a plane substantially parallel with the longitudinal axis of the leg of the user.

2. A swimming fin as in claim 1, wherein a toe supporting cushioned block is carried by the inner end of the fin member forwardly of the ball of the foot of the user.

3. A swimming fin as in claim 1, wherein the fin blade extends symmetrically with respect to the longitudinal axis of the foot on which the fin is placed.

4. A swimming fin as in claim 1, wherein the fin blade has a plurality of longitudinal ribs on opposite faces thereof converging towards the free end of the blade to increase the propulsive force of the fin.

5. A swimming fin as in claim 1, wherein the fin blade has a plurality of longitudinal ribs on opposite faces thereof converging towards the free end of the blade to increase the propulsive force of the fin and said ribs being of increased height at the side edges of the fin blade and gradually decreasing in height toward the longitudinal center of the fin blade.

6. A swimming fin as in claim 1, wherein the tin blade has a plurality of longitudinal ribs on opposite faces thereof converging towards the free end of the blade to increase the propulsive force of the fin, and spaced ribs between the aforesaid ribs arranged at an angle to the longitudinal axes of the longitudinal ribs.

7. A swimming fin as in claim 1, wherein the fin blade has a plurality of longitudinal ribs on opposite faces thereof converging towards the free end of the blade to increase the propulsive force of the fin and said ribs being of increased height at the side edges of the fin blade and gradually decreasing in height toward the longitudinal center of the fin blade, and spaced ribs between the aforesaid ribs arranged at an angle to the longitudinal axes of the longitudinal ribs.

References (Cited in the file of this patent UNiTED STATES PATENTS Re. 23,006 Churchill June 15, 1948 D. 132,377 Smith May 12, 1942 D. 161,536 Romano Ian. 2, 1951 2,423,571 Wilen July 8, 1947 

